The present invention concerns a shank milling cutter preferably for performing end milling operations.
Milling is a cutting machining process using a rotating tool. In that procedure the cutting edges produce the cutting movement by virtue of their rotation about the central axis of the tool. The advance movements can take place in various directions. They are effected by the tool or by the workpiece or even by both. In contrast to turning and drilling, the cutting edges are not constantly in engagement. After a cut on the workpiece they are returned in the disengaged condition to the point of first cut. As a result they can cool down and discharge the chips from the chip spaces.
In principle a distinction is made between three different milling cutting processes: peripheral milling, end milling and end-peripheral milling. Peripheral milling, also referred to as hob milling, is a milling process in which the major cutting edges which are at the periphery of the tool generate the desired workpiece surface; the milling cutter axis therefore extends parallel to the working surface and perpendicularly to the advance direction of the milling cutter. In the end milling process the desired workpiece surface to be produced is that to which the milling cutter axis is perpendicular and in that case the advance direction of the milling cutter is parallel to the workpiece surface produced. In that case however essential chip removal is also effected primarily with the major cutting edges arranged at the peripheral surface. The minor cutting edges which are at the end of the tool smooth the milled surface and thus produce the workpiece surface. Finally, in end-peripheral milling, both the major and also the minor cutting edges produce the desired workpiece surfaces.
Relatively high-grade surfaces can be produced by means of end milling. In that respect, the minor cutting edges are solely responsible for the surface produced. They move in one plane and not on a curved working surface like the major cutting edges which generate the workpiece surface in peripheral milling. Fine final machining of flat surfaces is possible with suitable end milling cutters.
The general view is that the quality of the particularly flat and smooth surfaces produced by end milling is essentially determined by the cutting edge corner shape and by the orientation of the minor cutting edges.
In order, however, to achieve a high level of surface quality by means of the conventional end milling cutters, the advance speed must be selected to be very low and the machining depth or chip thickness must be selected to be very slight, which in turn results in longer machining times and thus higher costs.
Therefore an object of the present invention is to provide a shank milling cutter with which milling, preferably end milling, can be effected at a high advance speed and a high level of chip removal efficiency with at the same time a high quality in respect of the machined surface.